<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        div{
            position: absolute;
        }
        .am{
            top: 210px;
            left: 210px;
        }
    </style>
</head>
<body>
<div id="test">1</div>
<div class="am">m</div>
<script>
       //判断角度 需要知道起点的算法  然后进行反推 就实现了
        var test=document.getElementById('test');
       var sinA =  (2*Math.PI / 360) * 210
       var sin=Math.sin(sinA);
       var cos =Math.cos(sinA);
      a=210;
      b=210;
     test.style.top= a+ 50 * sin +'px';
      test.style.left= b - 50 * cos +'px';
    console.log( 50 * cos-b);
        var cos1=b - 50 * cos;
       var sin2= 50 * sin + a ;
       console.log(sin2)
     var left=(cos1 - a) / 50;
     var a =(sin2 - a) / 50;
     console.log(cos)
     //
        console.log(a);
        var fasin=Math.acos(left);
     var fsain=Math.asin(a);
     //
      console.log(fasin)
      var v1= Math.abs( Math.round(fasin / (Math.PI / 180)) );
       var v2= Math.abs( Math.round(fsain/ (Math.PI / 180)) );
       if(v1 == v2){
           console.log('相等了');
       }


</script>
</body>
</html>